Anisotropic in-situ stretching-strain engineering of flexible multilayer thin-film nanogenerators with Cu interlayers

Enhanced charge carrier separation by bi-piezoelectric effects based on pine needle-like BaTiO3/ZnO continuous nanofibers

“…Thus, the piezoelectricity of ZnO is enhanced and the separation of photogenerated carriers is facilitated. 55,56…”

“…Thus, the piezoelectricity of ZnO is enhanced and the separation of photogenerated carriers is facilitated. 55,56 From the point of view of electron-hole migration, the interfacial electric eld between BaTiO 3 and ZnO continuously promotes the migration of electrons from the CB of BaTiO 3 to the CB of ZnO, which then migrate to the surface of ZnO. The CB value of ZnO is more negative than the O 2 /$O 2À redox potential, so that the electrons in the CB can undergo a reduction reaction with the dissolved oxygen in water to generate strong oxidizing free radicals.…”

Photothermal Structural Dynamics of Au Nanofurnace for In Situ Enhancement in Desorption and Ionization

“…As shown in Figure 5B, the wurtzite ZnO in the AuNI-ZNT was observed to be extended along the a-axis (0.123%) after 101.8 mJ cm −2 -laser irradiation, and the expansion along the c-axis (0.363%) was observed to be more prominent due to the anisotropic deformability of the ZnO. [12] As the AuNI nanofurnace produced a high surface temperature upon laser exposure, the dissipated heat thermally affected the neighboring ZNT structure. Further, as the Au metal (4.5 × 10 −5 K −1 ) has a much higher thermal expansion coefficient than the wurtzite ZnO (1.5 × 10 −5 K −1 ), thermal mismatch strain and tensile distortion were also induced in the ZNT.…”

“…[64] The increase in the values of c and c/a ratio with increasing laser fluence suggests the relative displacement of the Zn 2+ ion from the central position of the ZnO 4 unit along the c-axis. [12,65] The degree of ZnO 4 tetrahedra distortion with the applied laser pulse was further estimated using the ZnO bond length and the OZnO bond angles and visualized using the visualization for electronic and structural analysis (VESTA) software. Variations in structural parameters are described in Table S4 in the Supporting Information.…”

“…Matrix-assisted laser desorption/ionization mass spectrometry d 33 of ≈12.4 pC N −1 and an electromechanical coupling factor k 33 of ≈0.48. [9][10][11][12] Since a short-pulse laser can instantly produce mechanical stress by generating a shock wave, [13,14] piezoelectric potential can be developed inside the ZnO crystal, which forces the free carriers to move in opposite directions and extends their lifetimes. [15][16][17] However, it still remains inefficient in ZnO matrix-based LDI-MS due to the following three critical challenges: 1) ZnO has little impact on the analyte desorption because its photothermal conversion efficiency is poor, even though the desorption is primarily driven by a thermal process; 2) the recombination rate of charge carriers is high because photoinduced electrons/holes have strong abilities for reduction/oxidation, and accordingly they recombine with each other at the end; and 3) the method to induce an internal stress high enough for enhanced LDI-MS is rather limited in a ZnO nanostructure.…”